(5)No gas-holder, any lift of which has been in use for ten years,shall be used unless the internal condition to the sheeting is thoroughly examined by a competent person, by means of an electronic device or by a similar accurate device approved by the Chief Inspector and in case of any, gas-holder any lift of which has already been in use for ten years or more on the date on which this rule comes into force, such examination shall be carried out within the period of one year from the said date but, in exceptional cases such a period may be extended up to two years by the Chief Inspector. This examination shall be extended up to two years by the Chief Inspector. This examination shall be repeated once in every four years after the above mentioned first examination:Provided that if the Chief Inspector is satisfied that the devices mentioned in this sub-rule are not available, he may permit the examination to be carried out by cutting out samples from the crown and the sides of the gas-holder or other method approved by him:Provided further that if the above inspection raises any doubt, an internal visual examination shall be made.
